CONTEXT: Rabies postexposure prophylaxis (RPEP) treatments and associated costs have increased in the United States. The extent to which RPEP use is consistent with guidelines is not well understood.

OBJECTIVE: To characterize animal contacts and determine the frequency and factors associated with inappropriate RPEP use.

DESIGN, SETTING, AND PATIENTS: Prospective case series study of patients presenting with an animal exposure-related complaint from July 1996 to September 1998 at 11 university-affiliated, urban emergency departments (the Emergency ID Net).

MAIN OUTCOME MEASURES: Exposure type, circumstances, and RPEP use (appropriateness defined by local public health departments).

RESULTS: Of 2030 exposures, 1635 (81%) were to dogs; 268 (13%) to cats; 88 (4%) to rodents/rabbits; 10 (0. 5%) to raccoons; 5 (0.2%) to bats; and 24 (1.2%) to other animals. Among those exposed, 136 (6.7%) received RPEP after dog (95), cat (21), raccoon (8), bat (4), or other animal (8) exposures. Use of RPEP varied by site (range, 0%-27.7% of exposures), with most frequent use reported at sites in the eastern United States. Management was considered appropriate in 1857 exposures (91.5%). Use of RPEP was considered inappropriate in 54 cases (40% of those in which it was given), owing to factors including animal availability for observation and exposure in a low-endemicity area. Rabies postexposure prophylaxis was considered inappropriately withheld from 119 cases (6.3% of those not receiving RPEP), often because a domestic animal was unavailable for observation or testing.

CONCLUSION: These results suggest that use of RPEP is often inappropriate. Greater compliance with current guidelines would increase RPEP use. Physician education, improved coordination with public health officials, and clarification of RPEP guidelines could optimize use of this expensive resource.